Telephone system



April 1930. w M. ROSEKRANS 1,756,102

TELEPHONE SYSTEM Filed Feb. 23, 1929 A T TDR/VEY 2Q attended to by t e secretary- 7 so his own H111 Patented Apr. 29, 1930' UNITED STATES PATENT OFFICE w-rrrnnp M. ,ROSE7KR1NS,OF nroom'rrnrn, NEW JERSEY, Assrenoa 110' AMERICAN TELEPHONE AND rnnnsnnrn COMPANY, A CORPORATION or NEW YORK L H SYSTEM A ppl icationfiled February 23, 1929. Serial No. 342,184.

This inventionrelates to telephone systems andmore particularly to such systems equipped for secretarial service. I

It is common practice in large business establishlnentsto, employ telephone service of such a type that communications of minor importance, directed to their ofiicers, may be intercepted and handled by secretaries Without inconveniencingthe ofiicers. In order to 10 provide such facilities, secretarial service systems have been, employed, wherein calls intended for an ofiiceror principal are initially handled by a secretary who either consummatesthe call herself, or transfers it to the principal, if circumstances Warrant it. Usually, such systems also provide a direct line for the pri cipal. on whic calls of a strictly priva e naturemay be ans red by him, and which, during is absence, may be Here'tofore, this latter type of service did not insure strict privacy on calls incoming on the principals' line, but permitted the secretary'to have access to thejpr-incipals line .dur-

ing he co e of conve sation and to i n '',if she e e s disposedr, I It is the object o'fthis invention to insure, in secretarial service systems, absolute privacy tothe principal on calls incoming on v This obje'c't is attained in accordance with a feature of the'invention, by; the provision of an auxiliary tip relay in the principals line, which operates upon the removal of '35 the receiverat the principals station to preve th ecretary fromj pe a v ly a so i ing her sub etwiththe p'rincipals line.

rT e i venti n il' be re dily un s o d from the fo low ng. eta led d c ipt m d i to W h'reference to e a companyi g dra ing hich disclose a .191" .cipals'li e an a se eta y line ermina fna set ofkeys at c re arys positi n, by. virtue of which a secretary may answer calls on either line. Q11 a a l inc mingonthe' principa s l h operation o'w liing'ing c re t mequin eat at c ral flice o h wn); op rates ringing relay: which opens it beck contact and closes i s fron contac effecting a circuit for relay 7 which may be In attracting its right-hand armature relay 7 locks to ground on key 10 by way of the normal make-before-break contacts of relay 11. At its left-hand armature and front conestablishes a circuit from tact, relay 1 grounded battery 8, common bus-bar and fuse block, conductor 12, filament of line and busy lamp'lS, conductor 14, left-hand armature and front contact of relay 7, conductor 15, windings of relays 16 and 17 in series, conductor 18', back contact and inner armature of relay 19, to ground. Lamp signal 13 is lighted in this circuit and relays l6 and 17 operate. Relay 17 in attracting its armature establishes an obvious circuit for buzzer 20 which thereupon operates. v

Relay 17 in operating establishes a circuit for relay 21 extending from grounded battery 8, common bus-bar and fuse block, conductor 22, winding of relay 21, front contact and armature of relay 17 to ground.

Relay 21, at its armature and front contact establishes an operating circuit for relay 23, connecting it in parallel with its own winding in the circuit just traced. Relay 23 in like manner connects the Winding of relay 19 in parallel with its own Winding. Relay 19 thereupon operates and its back contact and armature opens the circuit herein'before traced, in Whichrelays 16 and 17 operated in series and line lamp 13 was lighted. Lamp 13 is thereupon extinguished and relays 16 and 17 restored to normal. Relay 16 opens the circuit for buzzer 20 which is thereupon silenced Relay 17 upon' restoring opens the circuit for relay 21 which in turn causes the release of relay 23. Relay 23, in like manner causes relay 19 to restore its armature to normal. Now the flashing circuit which comprises relays 17, 21, 23 and 19 is in its normal condition.

However, with relay 7 still operated,.relays 16 and 17 again operate in series andlamp 1 3 lighted in the same circuit hereinbe'fore the operation of relay 16. In response to sence of the principal the secretary may answer the call'in a manner hereinafter to be described.

Assuming'that the principal is available, he'proc'eeds toanswer the call in the usual nanner b'yfremoving the receiver, from the switch-hook at his sub-set 25. This action closes his line loop through the normally made contacts of key 26 whichis located at the secretar'ys position. Relays 2'7 and 28 thereupon'operateon current from the central otfice battery indicated at 29. V

I l/Vith relay 6 restored at the cessation of ringing, relays 30 and 11 now'operateiin parretarfys' line whlle the secretary 1s answering allelina circuit extending from grounded battery, common bus-bar and fuse block, conduc'tor] 9, thence inpara-llel throughwinding of relay ll'and front contact and armature of relay 27'," an'dwindin of relay130, "and front contact and armature 'of-irelay' 28 to ground by way of the back contact and armature of relay 6. Inattracting its armature, relay'30 disassociates conductors 38-and at which are-connectedto contacts of. the secretarys key 32,'from the principals line 5. By this arrangement it is impossible for the secretary to'connect her sub-set 33 to'the principals lineby the actuation of key 32, thereby insuring absolute privacy to the principal oncalls incoming on his'own line.

"Relay 11, operating as previously described, opens the locking circuit for relay 7 which thereupon releases and opens the flashing circuit whereupon lamp 13 ceases to flicker and burns-steadilyowing to the transfer of contacts effected by the operation of relay 11. The circuit in which lamp 13 is now lighted may be traced from grounded bat ery, COIXllllOIllJUS-bfll and fuse bloclr,';con ductor 12, filament of line lamp 13, condi'ictor'lt'inner right-hand armature and back contact of relay 35, armature and front contact of relayll, to ground at the normal contacts ofkey-10, The steady glow of lamp 13 serves as abusy signalat this time.

a At the. termination of conversation the principal hangs up the receiver thereupon opening the line loop 'and'causi-ng, the release of relays 2.7, and'28 which, in turn, cause-re lays 30 and 11Qto restore. The releaseiof these relays restores the circuit to normal condition and thecpr'incipals lineis ready for the next call..--;

' relay 35' which operates It is believed unnecessary to describe the tarys line as it is obvious that the secretarys line equipment is the sameas that of the principals line with the exception of that required for the cut-oif feature hereinbefore described, and which is individual to the principals line. The'fiashing'eireuit is common to'both'lines. v

. Should the principal .be bu y 21 absen when a call, such ashas becn described in detail, arrives on his line, the secretary noticing the continued flickering of the line lamp, may answer the callbyactuating transfer key 32 repose-iota e0 as tooperate the upper set of springcontacts. .This operation connects the conductors 38 and34leading'from the 'p1-incipa1s 1ine,,to c0ndu'ctors'39 and 4D, respectively, leading to th'esecretar'ys sub-set. The secretary is then in ,positionto converse with the party on theprincipals linef. The removal of the receiver at thelsecretarys'po- ;sition. resultsin the same operations as hereinbeforedescribedin connection with the answer' of acallby the principal. j, 7, f

In the event that a call comes in onthe seethe call-onjthe principalsv line,- she would hold the connection onjtheprincipals line and proceed to answerthe call oniher own cuit giving a steady signaltoiindicate a busy line.

The secretary then ope-rates 1261to position Bwhereupon relay 42 operates iii a circuit extending'fr'om' grounded battery; commonbus-bar' andfuse block, conductor 9, conductor 43, windingof relay 4:2,coi1d11cto'r 44, left-handalternate conta'etof key 32 (operated toA position), conductor 45, to ground on the alternate contactsef key 26 (operated to B position). Relay42 locks to ground on theicontact's of key 10,, by way of its own rightrhand armature and front contact and the armature and front contact o'f-relay 11.

At its left-hand armature and front contact relay" 42 connects ground to; thewindin'g of from battery 81by way of eonductor 9. 4 At its inner right-hand armature relay .35 opens the busy sign alieircuit toflamp 1'3'caus ing this lampj to i be extin uished. At. its

outeriright-hand armature relay 35 connects g een th ne; eiap ra p sisa o.

ring circuit for relay 35.

. 49, which circuit is completed to battery 8 by way of conductor 12. At its left-hand armature, it bridges the tip and ring conductors of the principals line 5 with the winding of relay 51 in series with resistance element 50. This connection serves as a holding bridge preventing the release of the connection on the principals line while the secretary answers a call on her own line. The left-hand armature of relay 35 also opens the shunt circuit, including resistance element 52, around relay 27, thereby giving this relay greater operating power while the holding circuit is across the line.

Relay 51 now operates from central ofiice battery indicated at 29, and prepares a lock- The purpose of this will appear presently.

The secretary then restores key 32 and operates it to position B. This operation causes the release of relay 27 which releases relay 11, the latter in turn releasing relay 42. Relay 42 removes ground from the winding of relay 35 which however does not restore owing to the locking circuit referred to in the preceding paragraph, which is now completed to ground at key 10 by way of the normal makebefore-break contacts of relay 11.

The connection on the principals line is now held by the holding bridge elfected by the operation of relay 35, and the secretarys subset 33 is connected to herown line 60 by virtue of the actuation of key 32 to position B.

When the call on the secretarys line is terminated the secretary actuates key 32 from position B to position A, again connecting her instrument with the principals line. Relay 27 again operates from central oflice battery by way of the closed loop through the secretarys instrument. Relay 27 causes relay 11 to function which in turn opens the locking circuit for relay 35. The release of relay 35 causes relay 51 to restore, hence the entire path of the holding circuit is opened. Re-

. lay35 also opens the circuit for hold lamp 49 and restores the original circuit for the busy lamp signal 13.

The secretary in like manner may hold a connection on herown line while attending a call on the principals line. It is believed that a detailed description of this operation is unnecessary as the description just com pleted is substantially applicable in every detail.

A call incoming on the secretarys line 60 and intended for the principal may be transferred to the principals station 25 by the actuation of key 26 to position A. This operation connects the line conductors of the serretarys line 60 to the principals sub-set and at the same time causes the transfer lamp 65 to be lighted in a circuit extending from grounded battery 8, common bus-bar and fuse block, conductor 12, filament of lamp 65, outermost left-hand alternate contact of key 26 in position A, conductor 66, winding of relay 67, normal make-before-break contacts of relay 68 to ground on the contacts of key 10.

fie hold lamp 70 and the line and busy lamp 71 associated with the secretarys line are lighted in the same manner and for the same purpose as lamps 49 and 31, respectively.

The key 10 is usually actuated when the business day is completed and neither the secretary nor principal is available to answer incoming calls. The actuation of this key prevents the lighting of lamps 13 and 17 and the operation of buzzer 20 on incoming calls when the equipment is unattended. This prevents any unnecessary drain on the local battery 8.

What is claimed is:

In a telephone system, a line, a signal associated with said line adapted to be actuated intermittently in response to a call incoming on said line, a station on said line, a second station, a key for connecting said second station with said line and means responsive to the seizure of said line at said first station in answer to the incoming call for altering the characteristic of said signal and rendering said key ineffective to connect said second station with said line.

In testimony whereof, I have signed my name to this specification this 19 day of February, 1929.

lVILFRED M. ROSEKRANS. 

